Process of agglomerating fibrous material.



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ING

AYPLIQ IIIIIIIIIIIIIIIIIII B.

UNITED STATES PATENT OFFICE.

CHARLES LADD NORTON, OF MANCHESTER, MASSACHUSETTS.

PROCESS OF AGGLOMERATING FIBROUS MATERIAL.

T o all whom it 'may concern:

Be it known that I, CHARLES LADD Non- TON, a citizen of the United States, and resident of Manchester, in the county of Essex and State of Massachusetts, have invented new and useful Improvements in Processes of Agglomerating Fibrous Material, of which the following is a specification.

My invention relates to the production of refractory material from mixtures containing fibious materials and solid or senil-solid cementitious matter, and initially, at least, a liquid which is usually required for the proper perfoiniance of the function of the cementitious material; and consists iii a process of agglomerating fibrous material whereby such refractory materials may be reduced with facility, rapidity, and uniormity; and the. effective con ition of the ress preserved indefinitelyY within the time limit of durability of the filter bed thereof.

Particularly, my new process relates to the production of refracttn material from substances of which asbestos is a type, for instancez-sucli refractory materials as are described in Letters Patent ol' the lfniled States, No. $47,293, granted to me under date of March 1'2, 1907.

Villiere, as in the easeA of the refractory niaterial described in my patent aforesaid, the ingredients which are subjected to pressure, (namely, the fibers; the ceineiitifious material and the liquid) are placed in a filter press, the removal ofthe surplus liquid from the mixture must be ell'ectuated in such maiiner that the liquid ex iressed muy not carry with it too much of the cenieiititious material, which, to perform its function properly, must remain in the body of the material together with a sufficient residual quantity of Water or other approlniate liquid to effect the setting of the cement. Consequently, if filtering material on a filter bed is relied upon to retain the finely coinininuted ceinentitous material, the mesh thereof must be extremely fine, in most cases as fine. as bolting cloth, if its functions are to be thoroughly performed.

While the employment of fine textile filtering material is mechanically feasible and effective to roduce slabs or sheets of refractory material of the general character above indicated, yet such filtering webs are undesirable and troublesome in a continuous series of operations, principally for the reason that they very soon become impregnated Specification of Letters Patent.

Application led July 6, 1908.

Patented July 27, 1909.

Serial No. 442,044.

with cementitious material which sets in the mesh and thereafter renders the filter useless,

and also because such filter Webs are fragile and ill suited to sustain heavy pressure, even though carefully supported. It is for this reason, I believe, that the manufacturers of certain refractory materials containing hydraulic cement have resorted to the formation of sheets by flowing a stream, composed of fibers (such as asbestos) hydraulic cement, and an abundance of Water, upon the webforming screens of paper machines, and have subsequently superposed sheets thus formed, after the manner of card board manufacture, rather than adopt treatment l y combined pressure and filtration, to form at one stroke a body of the desired weight and thickness, although a filter-pressed body containing the ingredients above named is superior in many respects to the laminated structure heretofore made.

My invention in its broader aspect, is characterized by the formation of a mixture of the essential ingredients, namely-fibers, solid or semi-soli cementitious material and a suitalle liquid, of such character and consistency, that when a mass of suoli mixture is spread upon a perforated metal screen, the fibers of the mixture Will, by interlacing and felting automatically and of themselves, form filtration webs over and across relatively large perforations in a filter sheet, so that these foundation fib'erstliei'nselves furnish a filter-web of fineness sufficient to retain within the body of the material the cementitious material, while allowing surplus liquid to be expressed. In properly compounded mixtures constituted principally of asbestos fibers, (even those very short fibers producen by the grinding of serpentine rock) these foundation fibers of the mixture form an effective retaining filtration web over apertures in a erforated metal sheet 1/16 in diameter. he physical condition essential to the performance of this function by the fibers in the mass under treatment is that the proportion of li uid in the material shall be less than that W ich `.vould produce mobility ofthe fibers in the liquid. If too much liquid is employed so that the fibrous ingredients of the material float about in it, as soon as the mixture is placed upon a filter bed provided only with a perforated metal sheet, the fibers themselves and a large portion of the cementitious material esca e through the perforations, thus depriving the mixture of part of a very essential ingredient, for the reason that the cemcntitious material is usually very finely commiiiuted. Again if the cementitious material, with or without a portion of the fiber, esca es through the mesh or perfor-ations in the fi ter bed, the spaces iii the filter bed soon become clogged and, as the ceinentitious material sets, the function al utility of the filter bed is destroyed, and if it be used in a hydraulic ress the filtration sheets and webs become iirmly cemented to the head of the press, from which they can be removed only with great difficulty. It is hardly necessary to state that, while the ro ortion of the liquid in the material should)beliess than' that which will reduce mobility of tlie'fibers therein, it shou d be at least sufficient for the purpose of combination with the cemcntitious material. This condition, however, is very easily secured without danger of exceeding the proper maximum limit.

In the drawings hereto annexed there is illustrated conventionally in part and on a very much enlarged scale, a portion of a filter press and its bed showing the characteristic behavior of a sell-filtering composition which embodies my invention.

The self-filtering compositions, broadly considered, which are described herein in order to illustrate my process, which is the subject of the. claims hereto appended, are described and reserved for claim in an application lor patent filed by me concurrently herewith, serially numberel 442,042; and 'thespecific selllfiltering composition coniposed of asbestif'orm fiber, magnesium oxid and water, also herein described, 'is described and reserved for claim in another application for patent, iiled by me concurrently herewith serially numbered 442,043.

As stated hereinabove, the compositions for the production of refractory material of the class to which my invention relates consist of fibers, eciiieiititious material and the liquid required for the functional o )eration of the ccinentitious material in an among the fibers. One takes, for instance, a mass of fibers of which asbestos is a type; these may be either asbestos fibers as ordinarily understood or may consist of the fibrous pul roduced by grinding the serpentine rocii rom which asbestos is mined. ith these fibers, preferably in a dry state, there is mixed a suitable quantity of dry hydraulic cement; suitable roportions are ten to twelve parts by weight of hydraulic cement (Portland cement) and twenty parts by weight of asbestos fiber. When these are thoroughly mixed, to the dry mixture there is added a quantity of water sufficient to effeet the proper setting of the cement, allowance being made for the Water which is subsequently to be pressed out of the material; but less than that quantity of Water which,

when thoroughly mixed with the fiber and cement, will render the fibers mobile in the liquid. Assuming that the solid ingredients mixed in the proper proportions above named are dry, a proper proportion will be iifty parts of water by weight. When this quantity of water is mixed thoroughly with the solid ingredients, the entire mass is of the consistency of a Wet mush of which the solid ortion will retain the water temporarily at east without allowing any sensible portion thereof to drain ofi or settle. This mixture is then placed upon the filter bed of the filter iress. i Referring to the drawings z-A and B represent the upper and lower press heads or press plates. -Ilpon the lower press plate tlrere`is laid a sheet of woven Wire E and over this 'a sheet of. perforated metal C. The perforations in this sheet C should be close to gethcr and preferably quite small, though they may, without impairing the success of the process, be as large as 1/16Il in diameter. Smaller perforations, even as small as 1/64 are, however, preferable for the reason that by the use of smaller perforations the lower surface of the finished compressed roduct is more nearly plane than it is when arger perforations are employed. Practice and oxperience with the particular mixture of materials used as ingredients of the article of manufacture produced will determine more exactlythe proper diameter and s acing of the a ertures inthe to of the dlter bed. 'lhe oiiject to be attaine is the formation of webs or nets composed of fibers which form an ingredient of thematcrial over and across the perforations in the filter bed sheet, and the preservation of these during the compression stage of the process so that, while surplus liquid will pass through the self-formed Webs of fiber, the cciiientitious material will be retained within the body of the article produced.

Referring again to the drawing, F represents the fibers in the mass under pressure, and the dots (not lettered) represent the particles of cemcntitious material. \'V hen the mixture as above described is spread upon the filter bed and subjected to pressure between the plates A and B, simultaneously with the flow of liquid through the apertures in the perforated sheet C the foundation fibprs mat together and form a web as at F stretched across the apertures" in the sheet C. This web possesses sufficient tensile strength to retain its integrity even though the ressure between the press plates A and exceeds one ton to the square inch. These Webs of the foundation fibers retain the cementitious material, while allowing surplus water to escape. When, after the compressed sheet or slab is removed from the ress, it'is examined closely, the lower surace of it will be found covered with slight the following protuberanccs, showinpr where the retaining webs ol' the foundation fibers have sagged slightly into the a )ei-tures of the top sheet of the filter bed, and it has also been observed in many instances that the cementitious inaterial is more dense immediately behind these little protuberances than elsewhere in the body ol' the finished article. This a)- parently demonstrates the tendency of the inely comminuted ceinentitious material to flow toward the apertures and to escape from the body oi' the mixture under pressure and also demonstrates the effectiveness of the self-formed webs of foundation liber to prevent the escape of the cemcntitious material from the body ol the mixture.

If the mixture under treatment is of the character described in my patent aforesaid,

q specifications are recommended: T he ingredients being asbestiform fiber, iinely divided magnesium oxid, and Water, one proceeds by first mixing in a dry state from 2% to 3 parts by weight of the asbestiform liber, with 1 part by weight of magnesium oxid7 the latter being,r preferably procured by the calcination of finely divided magnesium carbonate as set forth in my said patent. Then l part by'weight of this mixture of asbestiform fiber and magnesium oxid is mixed with 2 parts by weight of water. These proportions are correct provided the solids are thoroughly dry; if they have lain for any length ol' time in a moist atmosphere, water absorbed from the air must be taken account of. The correct manipulation and adjustment oi' the proportion of water Inechanically added must be learned by experience and checked by observation. The quality ol' thc wet mush and also the. behavior olf thc mixture in the press will serve as checks upon the operation ol water addition. 'l`oo litllc water will cause the compressedsheels or plates to adhere too inti mately to the press head and too much water will manil'est its excess by the quality of the liquid which llows from the press. The expressed liquid should run from the press nearly clear; if it is milk then it is certain that too much water is eing added to the material in the preparation for the press. A

-slight milkiness or cloudiness of the water which lirst emerges from the press will always be observed but is of no consequence. It is the subsequent flow of which the character serves as a detector of an excess of water in the mixture. Conversely, the character of the Waste-water from the ress for the same reason will betray errors 1n mixing the dry solid ingredients; if these involve too. scant proportions of' fiber, the mobility of the `bers in the liquid added will allow fiber and cement to pour through the filter perforations, and the expressed liquid will flow cloud throughout the operation. The mixe mass placed in the press is subjected to a pressure, preferably, of one ton or more to the square inch. The foundation fibers, as illustrated in the drawing, form retaining webs over the perforations in the upper sheet of the filter bed and retain magnesium oxid in the body of the article produced and insure the cementation of substantially the entire quantity of magnesium oxid originally incorporated in the mixture.

What I claim and desire to secure by Let! ters Patent is:

The process of agg]omeratiitgY material,

which consists 'in compressing a mass eor'nprising fibers, cementing' material and a stl ting liquid, meanwhile felting portions of the fou'ndationiibers in the mass into self-sus-V l taining l'iltration Webs, and externally supporting only those portions -offthe material.` as lie between said Webs, expressingr surplus liquid through said Webs, while retaining the cementing material thereon.

Signed by me at Boston, Massachusetts, 

